Vacuum Petcock?

Discussion in 'Engine, Fuel and Exhaust' started by Bodeen, Oct 11, 2009.

  1. Bodeen

    Bodeen Well-Known Member Staff Member Moderator Contributor

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    Having never had a vacuum operated petcock apart. Is it possible for fuel to pass through the vacuum line while running if the petcock were faulty? If the petcock were faulty ie: bad diaphram isnt the fuel supposed to shut off?

    TIA,

    Bodeen
     
  2. glider

    glider Veteran Member

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    The purpose of the vac petcock is to close off the fuel when the engine stops from lack of vacuum. The restart is accomplished by the fuel in the float bowl until the engine draws vacuum and opens the petcock. More problems for some than they are worth. Many have changed to a Pingle manual petcock or retro fitted to the regular HD mechanical petcock.

    Most times when they fail the engine just quits from lack of fuel.
     
  3. HDDon

    HDDon Experienced Member Contributor Retired Moderators

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    Glider has it right, get rid of the vacuum petcock and go for a Pingle.
     
  4. Bodeen

    Bodeen Well-Known Member Staff Member Moderator Contributor

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    Thanks guy's
    I figured if the diaphram were torn it would close off fuel supply.
    I was thinking that it would be possible for fuel to flow through the vacuum line to the carb adding extra fuel to the mix. I saw the self help section and the Pingle link. Proud of those jokers!

    Bodeen
     
  5. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    Maybe I'm a little...eh..."-new fashioned" here, but the vacuum petcock is a safety feature to prevent those of us who do not shut off the fuel when they park the bike for long periods...not that any of us "-old timers" would ever admit to anyway. There was a thread about a suitable replacement, for the rubber diaphragm for something like $5. :no

    Sorry, I just had to get it off my chest, and yes a replacement vacuum petcock is about the same price as the full Pingle replacement, but hey it's your decision. :33:
     
    Last edited: Oct 11, 2009
  6. nogoslim

    nogoslim Active Member

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    What years did harley put vacuum fuel shut off valves on their bikes, if at all? Did any efi bikes ever use a fuel shut off valve, vacuum or mechanical? If you put a fuel shut off on a newer e.f.i. bike, would it cause any damage to the regulator or fuel pump?
    :small3d004:
     
  7. SledDog

    SledDog Senior Member Staff Member Moderator

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    You can replace the vacuum petcock with a high flow "aftermarket" petcock for about $30.00.

    The OEM style vacuum one will cost you about 85 buck. I replaced the vacuum one on my road king with a high flow aftermarket unit last year and have had no problems. But I'm used to running off/on the gas. I did it even when I had the vacuum one on the road king.